Why do we sleep? One answer could be: to clear waste products accumulated during the day. To prevent aging and neurodegeneration, the body must maintain homeostasis. What would happen if we experience chronic sleep loss? What would happen if microgravity impairs the cerebrospinal fluid to flush the brain? What would happen if cosmic radiations increase the amount of daily waste products?
Loss of connectivity in the multisensory integration cortical areas after short term microgravity experience, which could explain astronauts decrease of performance in sensorimotor tasks and spatial working memory. However, the effect should wear off after a few days in microgravity and after adaptation to incongruent vestibular information. ISS experiment needed...